Mapping the SARS-CoV-2 spike glycoprotein-derived peptidome presented by HLA class II on dendritic cells.

Kevin O. Saunders, PhD, graduated from Davidson College in 2005 with a Bachelor of Science in biology. At Davidson College, he trained in the laboratory of Karen Hales, PhD, identifying the genetic basis of infertility. Saunders completed his doctoral research on CD8+ T cell immunity against HIV-1 infection with Georgia Tomaras, PhD, at Duke University in 2010. He subsequently trained as a postdoctoral fellow in the laboratories of Drs. Gary Nabel and John Mascola at the National Institutes of Health (NIH) National Institute of Allergy and Infectious Diseases (NIAID) Vaccine Research Center.

In 2014, Saunders joined the faculty at the Duke Human Vaccine Institute as a medical instructor. In this role, he analyzed antibody responses in vaccinated macaques, which led to the identification of glycan-dependent HIV antibodies induced by vaccination. Dr. Saunders was appointed as a non-tenure track assistant professor of surgery and the director of the laboratory of protein expression in the Duke Human Vaccine Institute in 2015. He successfully transitioned to a tenure-track appointment in 2018 and was later promoted to the rank of associate professor in surgery in 2020. In 2022, Saunders became an associate professor with tenure. He rose to the rank of professor with tenure in 2024 and was subsequently awarded the Norman L. Letvin, MD Professor in Immunology and Infectious Diseases Research in Surgery and the Duke Human Vaccine Institute distinguished professorship. Saunders previously served as DHVI's associate director of research, director or research, and currently serves as the associate director for DHVI. Additionally, Saunders serves as the faculty chairperson for DHVI's Diversity, Equity, and Inclusion Committee.

Saunders has given invited lectures at international conferences such as HIVR4P and the Keystone Symposia for HIV Vaccines. He has authored book chapters and numerous journal articles and holds patents on vaccine design concepts and antiviral antibodies. As a faculty member at Duke, Saunders has received the Duke Human Vaccine Institute Outstanding Leadership Award and the Norman Letvin Center For HIV/AIDS Vaccine Immunology and Immunogen Discovery Outstanding Investigator Award, Ruth and A. Morris Williams Faculty Research Prize, and the Duke Medical Alumni Emerging Leader Award. His current research interests include vaccine and antibody development to combat HIV-1, coronavirus, and other emerging viral infections.

About the Saunders Laboratory
The Saunders laboratory aims to understand the immunology of broadly protective antibodies and the molecular biology of their interaction with viral glycoprotein. The laboratory utilizes single B cell PCR, bulk B cell sequencing, and antigen-specific next-generation sequencing to probe the antibody repertoire during natural infection and after vaccination. The lab's overall goal is to develop protective antibody-based vaccines; therefore, the laboratory is divided into two sections–Immunoprofiling and Vaccine/Therapeutics design. They employ a reverse vaccinology approach to vaccine design where they study broadly protective antibodies in order to design vaccines that elicit such antibodies. To elicit broadly protective antibody responses, the Saunders laboratory utilizes epitope-focused nanoparticle vaccines. While eliciting broad protection is their overall goal, they are also interested in the immunologic mechanisms that make the vaccines successful.

Anti-glycan HIV-1 antibody biology. Their research premise is that vaccine-elicited antibodies will broadly neutralize HIV-1 if they can bind directly to the host glycans on Env. However, Env glycans are poorly immunogenic and require specific targeting by a vaccine immunogen to elicit an antibody response. Using this technique they identified two monoclonal antibodies from HIV Env vaccinated macaques called DH501 and DH502 that bind directly to mannose glycans and to HIV-1 envelope (Env). They have characterized these antibodies using glycan immunoassays, antibody engineering, and x-ray crystallography to define the mechanisms of Env-glycan interaction by these antibodies. Glycan-reactive HIV antibodies have mostly been found in the repertoire as IgG2 and IgM isotypes—similar to known natural glycan antibodies. Therefore they are examining whether vaccines mobilize antibodies from the natural glycan pool that affinity mature to interact with HIV-1 envelope. During this work, they discovered that Man₉GlcNAc₂ is the glycan preferred by early precursors in broadly neutralizing antibody lineages. They translated this finding into a vaccine design strategy that they have termed “glycan learning.” This approach modifies the number of glycans and type of glycosylation of HIV-1 Env immunogens to be optimal for engagement of the precursor antibody. The Env glycosylation sites and glycan type are then modified on subsequent Env immunogens to select antibodies that are maturing towards a broadly neutralizing phenotype. They have developed cell culture procedures and purification strategies combined with mass spectrometry analyses to create Env immunogens with specific glycosylation profiles. While the overall goal is to elicit protective neutralizing antibodies in vivo, they use these Env antigens in vitro to investigate the biology of B cell receptor engagement. 

HIV-1 Sequential vaccine design. The discovery of lineages of broadly neutralizing antibodies in HIV-infected individuals has provided templates for vaccine design. Utilizing viral sequences from individuals that make broadly neutralizing antibodies, we further engineer the viral protein to preferentially bind the desired type of antibody. The Saunders lab partners heavily with structural biologists and bioinformaticians to design optimized vaccine immunogens for in vitro and preclinical testing. They are investigating the hypothesis that broadly neutralizing antibodies can be engaged with envelope immunogens specifically designed to target them, and that engineered envelopes can select for the broadly neutralizing antibody precursors to develop into a broadly neutralizing antibody. They examine antibody responses in vaccinated humanized mice and monkeys to discern if the vaccine elicits antibodies that are similar to the known human broadly neutralizing antibody targets. Vaccines that are effective in animal models are translated for manufacturing and evaluation in Phase I clinical trials.

Pancoronavirus vaccine development. During the COVID-19 pandemic, the Saunders lab and DHVI as a whole worked to isolate broadly neutralizing antibodies against SARS-CoV-2 and related viruses. These antibodies then served as a template for the development of receptor binding domain nanoparticle vaccines we call RBD-scNP. These vaccines protected monkeys and mice from SARS-CoV-2 and animal coronaviruses. This vaccine has been translated to GMP manufacturing and will be examined in a Phase I clinical trial. The lab continues to apply similar approaches against other targets on coronaviruses to ultimately generate protective immunity against most coronaviruses. The lab explores different delivery methods including slow-release technology and nucleoside-modified mRNA delivery.

Taken together, our research program is an interdisciplinary approach to understanding the molecular biology underlying antibody recognition of viral glycoproteins in order to produce protective vaccines.

Barton F. Haynes, M.D. is the Frederic M. Hanes Professor of Medicine and Immunology, and Director of the Duke Human Vaccine Institute. Prior to leading the DHVI, Dr. Haynes served as Chief of the Division of Rheumatology, Allergy and Clinical Immunology, and later as Chair of the Department of Medicine. As Director of the Duke Human Vaccine Institute, Bart Haynes is leading a team of investigators working on vaccines for emerging infections, including tuberculosis, pandemic influenza, emerging coronaviruses, and HIV/AIDS.

To work on the AIDS vaccine problem, his group has been awarded two large consortium grants from the National Institutes of Health (NIH), National Institute of Allergy and Infectious Diseases (NIAID) known as the Center for HIV/AIDS Vaccine Immunology (CHAVI) (2005-2012), and the Center for HIV/AIDS Vaccine Immunology-Immunogen Discovery (CHAVI-ID) (2012-2019) to conduct discovery science to speed HIV vaccine development. In July 2019, his team received the third of NIH “CHAVI” awards to complete the HIV vaccine development work - CHAV-D.

Since the beginning of the COVID-19 pandemic, Haynes and the DHVI Team has been working non-stop to develop vaccines, rapid and inexpensive tests and therapeutics to combat the pandemic. Since March 2020, he has served as a member of the NIH Accelerating COVID-19 Therapeutic Interventions and Vaccines (ACTIV) committee to advise on COVID-19 vaccine development, and served as the co-chair of the ACTIV subcommittee on vaccine safety. Haynes is the winner of the Alexander Fleming Award from the Infectious Disease Society of America and the Ralph Steinman Award for Human Immunology Research from the American Association of Immunologists. He is a member of the National Academy of Medicine, National Academy of Inventors and the American Academy of Arts and Sciences.

About the Haynes Laboratory
The Haynes lab is studying host innate and adaptive immune responses to the human immunodeficiency virus (HIV), tuberculosis (TB), and influenza in order to find the enabling technology to make preventive vaccines against these three major infectious diseases.

Mucosal Immune Responses in Acute HIV Infection

The Haynes lab is working to determine why broadly neutralizing antibodies are rarely made in acute HIV infection (AHI), currently a major obstacle in the development of an HIV vaccine. The lab has developed a novel approach to define the B cell repertories in AHI in order to find neutralizing antibodies against the virus. This approach uses linear Immunoglobulin (Ig) heavy and light chain gene expression cassettes to express Ig V(H) and V(L) genes isolated from sorted single B cells as IgG1 antibody without a cloning step. This strategy was used to characterize the Ig repertoire of plasma cells/plasmablasts in AHI and to produce recombinant influenza mAbs from sorted single human plasmablasts after influenza vaccination.

The lab is also studying the earliest effect HIV-1 has on B cells. Analyzing blood and gut-associated lymphoid tissues (GALT) during acute HIV infection, they have found that as early as 17 days after transmission HIV-1 induces B cell class switching and 47 days after transmission, HIV-1 causes considerable damage to GALT germinal centers. They found that in AHI, GALT memory B cells induce polyclonal B cell activation due to the presence of HIV-1-specific, influenza-specific, and autoreactive antibodies. The team concluded from this study that early induction of polyclonal B cell differentiation, along with follicular damage and germinal center loss, may explain why HIV-1 induced antibody responses decline rapidly during acute HIV infection and why plasma antibody responses are delayed.

The lab is also looking at ways of generating long-lived memory B cell responses to HIV infection, another major hurdle in the development of a successful HIV-1 vaccine. The lab has found that in HIV-1 gp120 envelope vaccination and chronic HIV-1 infection, HIV-1 envelope induces predominantly short-lived memory B cell-dependent plasma antibodies.

Immunogen Design

To overcome the high level of genetic diversity in HIV-1 envelope genes, the Haynes lab is developing strategies to induce antibodies that cross-react with multiple strains of HIV. The lab has designed immunogens based on transmitted founder Envs and mosaic consensus Envs in collaboration with Dr. Bette Korber at Los Alamos National Laboratory. These immunogens are designed to induce antibodies that cross-react with a multiple subtype Env glycoproteins. The goal is to determine if cross-reactive mAbs to highly conserved epitopes in HIV-1 envelope glycoproteins can be induced. The team recently characterized a panel of ten mAbs that reacted with varying breadth to subtypes A, B, C, D, F, G, CRF01_AE, and a highly divergent SIVcpzUS Env protein. Two of the mAbs cross-reacted with all tested Env proteins, including SIVcpzUS Env and bound Env proteins with high affinity.

Mucosal Immune Responses in TB and Influenza

The Haynes lab is helping to develop novel approaches to TB vaccine development. The current therapeutic vaccine for TB, called BCG, may prevent complications from TB in children, but offers little protection against infection and disease in adults. The lab is focused on using live attenuated Mycobacterium tuberculosis mutants as vaccine candidates and is currently evaluating this approach in non-human primate studies. As part of the DHVI Influenza program, they are studying the B cell response to influenza in order to generate a “universal” flu vaccine. They are currently trying to express more highly conserved influenza antigens in recombinant vesicular stomatitis virus (rVSV) vectors in order to elicit robust T cell and antibody responses to those antigens.